I think the best is to assume the backups are lost.
From the iCloud terms and conditions:
Backup
Automatic backup is available for iOS devices, and occurs periodically, when the device is screen locked, connected to a power source, and connected to the Internet via a Wi-Fi network. iCloud will store your last three backups; however, if a device has not backed up to iCloud for a period of one hundred and eighty (180) days, Apple reserves the right to delete the backups associated with that device. Backup is limited to device settings, device characteristics, photos and videos, messages (iMessage, SMS, and MMS), ringtones, app data, location settings (such as location-based reminders that you have set up), and Home screen and app organization. Content purchased from the iTunes Store, App Store, or iBookstore is not backed up, but may be eligible for download from those services, subject to account requirements, availability, and the applicable terms and conditions. Media obtained from other sources (such as imported music or home videos) are not backed up, but can be synced from your computer by using iTunes. Your iCloud email, contacts, calendars, bookmarks, and documents are stored in, and can be accessed from, iCloud. Apple shall use reasonable skill and due care in providing the Service, but, TO THE GREATEST EXTENT PERMISSIBLE BY APPLICABLE LAW, APPLE DOES NOT GUARANTEE OR WARRANT THAT ANY CONTENT YOU MAY STORE OR ACCESS THROUGH THE SERVICE WILL NOT BE SUBJECT TO INADVERTENT DAMAGE, CORRUPTION, LOSS, OR REMOVAL IN ACCORDANCE WITH THE TERMS OF THIS AGREEMENT, AND APPLE SHALL NOT BE RESPONSIBLE SHOULD SUCH DAMAGE, CORRUPTION, LOSS, OR REMOVAL OCCUR. It is your responsibility to maintain appropriate alternate backup of your information and data.
